Erodable material

ABSTRACT

An improved material useful for a multitude of purposes which will dissolve or degrade in a short period of time when exposed to water, water vapor or sunlight. The material includes an intermediate layer of water soluble thermoplastic material with a layer of polyethylene film on both sides thereof. When the material is exposed to normal atmospheric conditions, the intermediate water soluble layer will ultimately dissolve. The thin outer and inner layers will degrade to a powdery film.

United States Patent Richardson et al.16l/252 Ma ki Dec. 12, 1972ERODABLE MATERIAL 3,214,291 10/1965 Dixler ..117/138.8 PV [72] Inventor:William L. Mackie, 394 Court 22 23 22 3113?? g i s hggfig 1 Avenue,Ventura, Calif. 93003 83 a e a [22] Filed: Sept. 18, 1970 OTHERPUBLlCATlONS [21] AppL 73 4 9 Leach, 0., Plastics Can Disintegrate,'SayBritish,"

7 The Washington Post; p. A14, 7/20/70 [52] US. Cl ..2l5/1 C, 1 17/76 F,117/138.8 PV, primary m p Burnett 161/165 161/252 161/406 AssistantExaminerGeorge W. Moxon, 11

220/54. 22O/DIG- 30 Attorney-Richard S. Sciascia, Q. Baxter Warner and Ilit. Cl. Gayward Mann [58] Field of Search ..161/165, 252, 254. 406; I

1 17/76 F. 138.8 PV; 215/1 C; 220/D1G. 30 [57 ABSTRACT An im rovedmaterial useful for a multitude of ur- 56 R r c: d P P l e erences I eposes which will dissolve or degrade in a short period UNITED STATESPATENTS of time when exposed to water, water vapor or sunlight. Thematerial includes an intermediate layer of 2 32 O Nell "229/5118 watersoluble thermoplastic material with a layer of I ll 8 wbber Cpolyethylene film on both sides thereof. When the 3l86'869 6/1965 F l17/ l38'8 Pv material is exposed to normal atmospheric conditions, 1on9Gnffin "no/D1630 the intermediate water soluble layer will ultimately3,107,199 l0/l963 TOCkCl' "161/252 dissolve The thin outer and innerlayers will degrade 2,897,108 7/1959 Harwood ..16l/l65 toapowdery film.3,282,729 11/1966 4 Claims, 3 Drawing Figures ERODABLE MATERIALSTATEMENT OF GOVERNMENT INTEREST The invention described herein may bemanufactured and used by or for the Government of the United States ofAmerica for governmental purposes without the payment of any royaltiesthereon or therefor.

BACKGROUND OF THE INVENTION 1. Field of the Invention.

This invention relates to an erodable material and more particularly toan erodable material useful in fabricating containers, sacks, wrappingmaterial, etc., which disintegrates in a relatively short time uponexposure to normal environmental conditions.

2. Description of the Prior Art.

Most containers, such as bottles, cans and the like, are of a permanentnature and are capable of being reused numerous times. However, whendiscarded these containers pose a threat to the environment by reason oftheir permanent nature. Steel containers will rust away in a few yearsif exposed to environmental conditions but aluminum and glass containerssurvive indefinitely. Newly developed plastic containers also survivefor a long period of time. Thus such containers accumulate to litter theworlds streets and highways and pose a threat to the environment.

The present invention solves this distressing problem by providing anerodable material from which con tainers may be fabricated, saidcontainers being destroyed by the natural elements of the atmosphere.

SUMMARY OF THE INVENTION The present invention is an erodable materialuseful for sundry purposes which will degrade and dissolve or becomedecomposed in-a relatively short period of time when exposed to thenatural conditions of the environment. The structure of the materialincludes an inner and outer layer of clear, low-density polyethylenefilm surrounding an interior layer of soluble thermoplastic resin. Thepolyethylene is photo-degradable whereas the intermediate material iswater soluble. When the interior material is exposed to environmentalmoisture it will dissolve. The polyethylene inner and outer layers willdegrade in response to the deleterious effects of sunlight.

STATEMENT OF THE OBJECTS OF THE INVENTION A primary use for the materialof this invention is in the construction of containers which dissolve ordegrade when opened.

Accordingly it is an object of the present invention to provide amaterial which erodes when subject to the deleterious effects of theenvironment.

Another object of the present invention ,is to provide a container whichis destroyed by the natural conditions of the environment.

Another object is to provide a container for fluids or beverages whichwill dissolve or erode away within a relatively short time after beingopened.

It is a further object to provide a container having a wall with atleast three separate degradable layers which after being opened willdegrade in response to the natural elements of the environment.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of acontainer embodying the material of the present invention.

FIG. 2 is a similar view of the container of FIG. 1 showing a strip ofcontainer wall removed to expose an intermediate layer of the material.

FIG. 3 is a cross sectional view showing a portion of the laminatedcontainerwall taken along the line 3-3 I of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention comprises alaminated material readily formed into a container or like device usefulfor sundry purposes which material after opening of the container willdegrade in a relatively short period of time in response to naturalenvironmental conditions including water, water vapor and sunlight.

In the embodiment shown the wall 12 of container 10 is fabricated from asheet material having at least three layers and as illustrated in FIG. 3may include an outer layer of polyethylene film 14, an interior orintermediate layer of a water soluble resin 16 and an inner layer ofpolyethylene film 18 immediately adjacent the product carried within thecontainer. The intermediate layer 16 of thermoplastic resinous materialcomprises the major portion of the wall 12 while the outer and innerlayers 14 and 18 respectively are relatively thin, being approximately.001 inch in thickness.

In operation a tab 20 on the top surface 22 of container 10 is pulledwhich opens the container in the conventional manner along the scoredmarks 24. However, the tab 20 is also pulled downwardly along the wall12 which removes a narrow band 26 of the outer polyethylene material 14exposing the water soluble intermediate layer 16 to the weather. Theintermediate layer will ultimately dissolve while the very thin innerand outer layers of polyethylene photo-degrade to a powdery residue.Degradation time of the entire container will depend on the disposallocation because the annual rainfall and the suns intensity will governthe time required for the container to completely disappear.

There are numerous materials which may be employed as the water solubleresins of the intermediate layer. Some of these are ethylene oxide,water soluble polyvinyl alcohol, carboxymethyl cellulose, hydroxyethylcellulose and polyethylene glycol. Polyethylene oxide is the preferredmaterial. It is soluble in water but resistant to oils and gases as wellas biological attack. It is also low in toxicity which is an advantagein food or beverage containers.

Polyvinyl alcohol is also completely soluble in water and is unaffectedby oils, greases and petroleum hydrocarbons. It is also impervious tomost gases, a distinct advantage in some food products which containdissolved gases.

The thin outer and inner layers are preferably both made of polyethylenedue to its excellent resistance to water, oils and gases and fairresistance to gas transmission. Moreover it is approved by the Food andDrug Administration for use in food packaging operations.

Polyethylene is adversely affected by ultra-violet light and willdegrade eventually to a powdery mass. The inner layer 18 which is indirect contact with a food or beverage must be resistant to chemicalaction by chemical constituents in the food or beverage. It must also beimpervious to dissolved gas in the food or beverage such as carbondioxide. For most purposes, polyethylene would suffice, but for foods orbeverages having a high content of dissolved gas it may be necessary toline the inner polyethylene layer 18 with a gasimpermeable coating. Suchcoating would be very thin, substantially about 0.005 inch. Manymaterials would suffice for this purpose but polypropylene which has avery low gas permeability rate is preferred.

While the foregoing embodiment describes a container 10, it is clearthat the erodable material from which the container is fabricated may beemployed for sundry other purposes including sacks, wrapping materialand the like.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

I claim:

1. A disposable container which is degraded by the natural elements ofthe environment, the structure of said container consisting essentiallyof:

an interior layer of water soluble resinous material selected from thegroup consisting of ethylene oxide, water soluble polyvinyl alcohol,carboxymethyl cellulose, hydroxyethyl cellulose and polyethylene glycolsaid interior layer forming the major portion of the compositestructure;

an outer layer of photo-degradable polyethylene an inner layer ofphoto-degradable polyethylene film, both the inner and outer layersabout .001 inch in thickness;

means for opening said container, said means adapted to strip away aband of outer polyethylene film, exposing the water soluble intermediatelayer to the moisture of the environment which then dissolves while theouter and inner layers will degrade to a powder.

2. The disposable container of claim 1 wherein said means for openingthe container includes:

a pull tab mounted on the top surface of said container and attached toa scored strip of the polyethylene outer layer of said container wall;

thus the top surface of said container is conventionally removed whilesimultaneously removing a narrow band of the outer polyethylene materialwhich exposes the water soluble intermediate layer to environmentalmoisture dissolving the same while the outer and inner layers degrade toa 3. l ii d i s posable container of claim 2 wherein said container is acan.

4. A disposable container which is degraded by the natural elements ofthe environment, the structure of the container consisting essentiallyof:

an interior layer of water soluble resinous material selected from thegroup consisting of ethylene oxide, water soluble polyvinyl alcohol,carboxymethyl cellulose, hydroxyethyl cellulose and polyethylene glycol,said interior layer forming the major portion of the compositestructure;

an outer layer of photo-degradable polyethylene film;

an inner layer of photo-degradable polyethylene film, both the inner andouter layers being about 0.001 inch in thickness;

21 gas-impermeable coating of polypropylene lining the innerpolyethylene layer, said layer of polypropylene being about 0.005 inchin thickness;

means for opening said container, said means adapted to strip away aband of outer polyethylene film, exposing the water soluble intermediatelayer to the moisture of the environment which then dissolves while theouter and inner layers will degrade to a powder.

2. The disposable container of claim 1 wherein said means for openingthe container includes: a pull tab mounted on the top surface of saidcontainer and attached to a scored strip of the polyethylene outer layerof said container wall; thus the top surface of said container isconventionally removed while simultaneously removing a narrow band ofthe outer polyethylene material which exposes the water solubleintermediate layer to environmental moisture dissolving the same whilethe outer and inner layers degrade to a powder.
 3. The disposablecontainer of claim 2 wherein said container is a can.
 4. A disposablecontainer which is degraded by the natural elements of the environment,the structure of the container consisting essentially of: an interiorlayer of water soluble resinous material selected from the groupconsisting of ethylene oxide, water soluble polyvinyl alcohol,carboxymethyl cellulose, hydroxyethyl cellulose and polyethylene glycol,said interior layer forming the major portion of the compositestructure; an outer layer of photo-degradable polyethylene film; aninner layer of photo-degradable polyethylene film, both the inner andouter layers being about 0.001 inch in thickness; a gas-impermeablecoating of polypropylene lining the inner polyethylene layer, said layerof polypropylene being about 0.005 inch in thickness; means for openingsaid container, said means adapted to strip away a band of outerpolyethylene film, exposing the water soluble intermediate layer to themoisture of the environment which then dissolves while the outer andinner layers will degrade to a powder.